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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 17 |
| 7 | 46 |
| 8 | 128 |
| 9 | 373 |
| 10 | 1119 |
| 11 | 3405 |
| 12 | 10464 |
| 13 | 32478 |
| 14 | 101781 |
| 15 | 321642 |
| 16 | 1023512 |
| 17 | 3276326 |
| 18 | 10543100 |
| 19 | 34088806 |
| 20 | 110690682 |
| 21 | 360810160 |
| 22 | 1180195810 |
| 23 | 3872588051 |
| 24 | 12743937024 |
| 25 | 42049240694 |
| 26 | 139082885503 |
| 27 | 461072582522 |
| 28 | 1531697761470 |
| 29 | 5098246648103 |
| 30 | 17000237006441 |
[1,1,1,2,6,17,46,128,373,1119,3405,10464,32478, 101781,321642,1023512,3276326,10543100,34088806, 110690682,360810160,1180195810,3872588051, 12743937024,42049240694,139082885503,461072582522, 1531697761470,5098246648103,17000237006441] |